The disclosure of my U.S. Pat. No. 5,493,785, issued Feb. 27, 1996, is included herein in its entirety by reference.
Rotary vegetation mowers using both string and rigid steel blades are well known in the art including those that use a replaceable nail as a cutting blade.
A significant problem in the prior art for edgers or hedge trimmers that are manually portable is the heavy weight and high power requirements for accomplishing such functions as the cutting of hedges where a cutter can encounter stalks too tough to routinely cut.
A general problem is that rotary mowers are not usually adaptable to different kinds of vegetation cutting challenges. Thus tender newly sprouted grass cutting requires drastically different conditions than mature wiry strains of grass, and weeds that may need to be cut as well.
A more specific problem is that a rigid rotary cutting blade may snap or cause catastrophic failure if it hits a foreign object such as a rock, wire or tree root in the course of mowing. That has been addressed in part in the prior art by providing rotary mounts for the cutting blades. Thus, an encounter with a foreign object when mowing will usually permit the blade to recover. An example of such a mowing implement is U.S. Pat. No. 4,345,420 issued to P. A. Oesterling, et al. Aug. 24, 1982 which rotatably mounts a cutter blade upon a peg rigidly mounted near the periphery of and between two separated rotatable discs.
However, such mechanisms generally improperly distribute weight toward the outer cutting periphery which will slow down the rotation speed and require additional mowing power.
Also such mechanisms are not adaptable to a wide range of mowing conditions. For example blades are not designed to cut over a range of grass lawns when weeds are encountered, brush and other vegetation forms. It would be most unusual to have rotary cutting heads that are adaptable to a wide range of conditions including hedge cutters that encounter woody branches.
Accordingly it is an object of this invention to improve the state of the rotary mower art with a novel versatile, light-weight, multiple-use cutting head.